Therapeutic contact lenses with anti-fungal delivery

ABSTRACT

A drug delivery system is disclosed. The drug delivery system includes a recognitive polymeric hydrogel through which a drug is delivered by contacting biological tissue. The recognitive polymeric hydrogel is formed using a bio-template, which is a drug or is structurally similar to the drug, functionalized monomers, preferably having complexing sites, and cross-linking monomers, which are copolymerized using a suitable initiator. The complexing sites of the recognitive polymeric hydrogel that is formed preferably mimic receptor sites of a target biological tissue, biological recognition, or biological mechanism of action. A system in accordance with an embodiment of the invention is a contact lens for delivering a drug through contact with an eye. In a particular embodiment of the invention, the drug is an anti-microbial, such as an anti-fungal agent for treatment of large animals, such as horses.

RELATED APPLICATIONS

This application is a Continuation-in-part of the co-pending applicationSer. No. 11/346,770, filed Feb. 3, 2006, and titled “Contact DrugDelivery System,” which claims priority under 35 U.S.C. §119(e) of theco-pending U.S. Provisional Application Ser. No. 60/692,042, titled“Sustained Ophthalmic Drug Delivery Via Biomimetic Recognitive ContactLens,” filed Jun. 17, 2005, the U.S. Provisional Application Ser. No.60/736,140, titled “Sustained Ophthalmic Drug Delivery Via BiomimeticRecognitive Contact Lens,” filed Nov. 10, 2005, and the U.S. ProvisionalApplication Ser. No. 60/650,450, titled “Enhanced Loading and ExtendedRelease Contact Lens for Histamine Antagonist Drug Ketotifen,” filedFeb. 4, 2005.

This application also claims priority under 35 U.S.C. §119(e) of theco-pending U.S. Provisional Application Ser. No. 60/858,584, titled“Therapeutic Contact Lenses with Anti-fungal Delivery,” filed Nov. 13,2006. The co-pending application Ser. No. 11/346,770, filed Feb. 3,2006, and titled “Contact Drug Delivery System,” the U.S. ProvisionalApplication Ser. No. 60/692,042, titled “Sustained Ophthalmic DrugDelivery Via Biomimetic Recognitive Contact Lens,” filed Jun. 17, 2005,the U.S. Provisional Application Ser. No. 60/736,140, titled “SustainedOphthalmic Drug Delivery Via Biomimetic Recognitive Contact Lens,” filedNov. 10, 2005, the U.S. Provisional Application Ser. No. 60/650,450,titled “Enhanced Loading and Extended Release Contact Lens for HistamineAntagonist Drug Ketotifen,” filed Feb. 4, 2005 and the co-pending U.S.Provisional Application Ser. No. 60/858,584, titled “Therapeutic ContactLenses with Anti-fungal Delivery,” filed Nov. 13, 2006 are all herebyincorporated by reference.

FIELD OF THE INVENTION

The invention relates to drug delivery systems. More specifically, thisinvention relates to systems for and methods of time released ophthalmicdrug delivery using contact lenses.

BACKGROUND OF THE INVENTION

Delivering medications via contact lenses has been a prevailing practicesince the inception of using hydrophilic, crosslinked polymer gels onthe surface of the eye. In fact, the first patent in the field from OttoWichterle in 1965 states that “bacteriostatic, bacteriocidal orotherwise medicinally active substances such as antibiotics may bedissolved in the aqueous constituent of the hydrogels to providemedication over an extended period, via diffusion.” However, there isevidence that this notion of a dissolved component in an aqueousconstituent has been around for a much longer period of time. Evidenceexists that honey soaked linen was used in ancient Rome as an ophthalmicdressing in the treatment of disease.

The biggest obstacle to using the fluid entrained in the aqueous portionof the polymer gel is maintaining a significant concentration of drugwithin the fluid to have a therapeutically relevant effect, which isultimately limited by the solubility of the drug. This has been theprimary reason why drug release from contact lenses has not become aclinical or commercial success. To an equivalent extent, the controlover the drug delivery profile and an extended release profile is alsoimportant to therapeutic success and has not been demonstrated usingthese methods. Drug uptake and release by conventional (i.e., currentlyavailable) soft contact lenses can lead to a moderate intraocularconcentration of drug for a very short period of time, but does not workvery well due to a lack of sufficient drug loading and poor control ofrelease. The use of soft, biomimetic contact lens carriers (i.e.,recognitive polymeric hydrogels) described herein has the potential togreatly enhance ocular drug delivery by providing a significant designedand tailorable increase in drug loading within the carrier as well asprolonged and sustained release with increased bioavailability, lessirritation to ocular tissue, as well as reduced ocular and systemic sideeffects.

The ocular bioavailability of drugs applied to the eye is very poor(i.e., typically less than 1-7% of the applied drug is absorbed with therest entering the systemic circulation). Factors such as ocularprotective mechanisms, nasolacrimal drainage, spillage from the eye,lacrimation and tear turnover, metabolic degradation, and non-productiveadsorption/absorption, etc., lead to poor drug absorption in the eye.Currently, more efficient ocular delivery rests on enhancing drugbioavailability by extending delivery and/or by increasing drugtransport through ocular barriers (e.g., the cornea—a transparent,dome-shaped window covering the front of the eye; the sclera—the tough,opaque, white of the eye; and the conjunctiva—a mucous membrane of theeye with a highly vascularized stroma that covers the visible part ofthe sclera). A topically applied drug to the eye is dispersed in thetear film and can be removed by several mechanisms such as:

-   -   (i) irritation caused by the topical application, delivery        vehicle, or drug which induces lacrimation leading to dilution        of drug, drainage, and drug loss via the nasolacrimal system        into the nasopharynx and systemic circulation (e.g., the rate        drainage increases with volume);    -   (ii) normal lacrimation and lacrimal tear turnover (16% of tear        volume per minute in humans under normal conditions);    -   (iii) metabolic degradation of the drug in the tear film;    -   (iv) corneal absorption of the drug and transport;    -   (v) conjunctival absorption of the drug and scleral transport;    -   (vi) conjunctival “non-productive” absorption via the highly        vascularized stroma leading to the systemic circulation; and    -   (vii) eyelid vessel absorption leading to systemic circulation.

Therefore, due to these mechanisms, a relatively low proportion of thedrug reaches anterior chamber ocular tissue via productive routes suchas mechanisms (iv) and (v).

For posterior eye tissue and back of the eye diseases (e.g., age-relatedmacular degeneration, retinal degeneration, diabetic retinopathy,glaucoma, retinitis pigmentosa, etc.), the amount of drug delivered canbe much less compared to front of the eye disease. To treat back of theeye disease, four approaches have typically been used, topical, oral(systemic delivery), intraocular, and periocular delivery.

Topically applied drugs diffuse through the tear film, cornea/sclera,iris, ciliary body, and vitreous before reaching posterior tissues, butdue to the added transport resistances such diffusions do not typicallylead to therapeutically relevant drug concentrations. However,researchers have shown that topically applied drugs do permeate throughthe sclera by blocking corneal absorption and transport. Intravitrealinjections (injections into the eye) require repeated injections andhave potential side effects (hemorrhage, retinal detachment, cataract,etc.) along with low patient compliance. Extended release devices havebeen used but require intraocular surgery and often have the sameincidence of side effects. Periocular drug delivery is less invasive andalso requires injections or implant placement for predominantlytransscleral delivery.

To overcome most of these protective mechanisms, topical formulationshave remained effective by the administration of very highconcentrations of drug multiple times on a daily basis. For a number ofdrugs high concentrations can lead to negative effects such as burning,itching sensations, gritty feelings, etc., upon exposure of themedication to the surface of the eye as well as increased toxicity andincreased ocular and systemic side effects. However, traditionalophthalmic dosage forms such as solutions, suspensions, and ointmentsaccount for 90% of commercially available formulations on the markettoday. Solutions and suspensions (for less water soluble drugs) are mostcommonly used due to the ease of production and the ability to filterand easily sterilize them. Ointments are used to a much lesser extentdue to vision blurring, difficulty in applying to the ocular surface,and greasiness. The term “eye drops” herein refers to all topologicalmedications administered to a surface of the eye, including but notlimited to solutions, suspensions, ointments and combinations thereof.In addition to the aforementioned problems, drug delivery through theuse of eye drops does not provide for controlled time release of thedrug. Eye drop medications typically have a low residence time of thedrug on the surface of the eye.

The efficacy of topical solutions has been improved by viscosityenhancers that increase the residence time of drugs on the surface ofthe eye, which ultimately lead to increased bioavailability as well asmore comfortable formulations. Also, inclusion complexes have been usedfor poorly soluble drugs, which increase solubility without affectingpermeation.

Other recent delivery methods have included in situ gel-forming systems,corneal penetration or permeation enhancers, conjunctival muco-adhesivepolymers, liposomes, and ocular inserts.

Ocular inserts, in some cases, achieve a relatively stable or constant,extended release of a drug. For example, ocular inserts such as Ocusert®(Alza Corp., FDA approved in 1974) consist of a small wafer thatcontains a drug reservoir enclosed by two ethylene-vinyl acetatecopolymer membranes. The wafer is placed in the corner of the eye andprovides extended release of a therapeutic agent for approximately 7days (e.g., pilocarpine HCL, for glaucoma treatment, reducingintraocular pressure on the eye by increasing fluid drainage). Lacrisert(Merck) is a cellulose based polymer insert used to treat dry eyes.However, inserts have not found widespread use due to occasional noticedor unnoticed expulsion from the eye, membrane rupture (with a burst ofdrug being released), increased price over conventional treatments, etc.

Mucoadhesive systems and in-situ forming polymers typically haveproblems involving the anchorage of the carrier as well as ocularirritation resulting in blinking and tear production. Penetrationenhancers can cause transient irritation, or alter normal protectionmechanisms of the eye, and some agents can cause irreversible damage tothe cornea.

SUMMARY OF THE INVENTION

The present invention is directed to drug delivery methods and systems.A drug delivery system in accordance with the present invention includesa recognitive polymeric hydrogel through which a drug is delivered bycontacting biological tissue. The recognitive polymeric hydrogel isformed using a bio-template, which is a drug or is structurally similarto the drug, functionalized monomers, preferably having complexingsites, and cross-linking monomers, which are copolymerized using asuitable initiator, such as described in detail below. The complexingsites of the recognitive polymeric hydrogel that is formed preferablymimics receptor sites of a target biological tissue, biologicalrecognition, or biological mechanism of action. The system unitizes whatis referred to herein as a biomimetic recognitive polymeric hydrogel.

A system in accordance with one embodiment, is an ophthalmic drugsystem. The ophthalmic drug system includes soft contact lenses formedfrom the biomimetic recognitive polymeric hydrogel. The lenses areimpregnated with a drug that can be released over a duration of timewhile in contact with eyes. The invention is directed to both correctiveand refractive contact lenses as well as non-corrective andnon-refractive contact lenses. While the invention as described hereinrefers primarily to ophthalmic drug systems, it is understood that thepresent invention has applications in a number of different contact drugdelivery systems. For example, the biomimetic recognitive polymerichydrogel can be used in bandages, dressings, and patch-type drugdelivery systems to name a few.

In accordance with the embodiments of the invention a hydrogel matrixthat is formed from silicon-based cross-linking monomers, carbon basedor organic-based monomers, macromers or a combination thereof. Suitablecross-linking monomers include but are not limited to Polyethyleneglycol (200) dimethacrylate (PEG200DMA), ethylene glycol dimethacrylate(EGDMA), tetraethyleneglycol dimethacrylate (TEGDMA),N,N′-Methylene-bis-acrylamide and polyethylene glycol (600)dimethacrylate (PEG600DMA). Suitable silicon-based cross-linkingmonomers can include tris(trimethylsiloxy)silyl propyl methacrylate(TRIS) and hydrophilic TRIS derivatives such astris(trimethylsiloxy)silyl propyl vinyl carbamate (TPVC),tris(trimethylsiloxy)silyl propyl glycerol methacrylate (SIGMA),tris(trimethylsiloxy)silyl propyl methacryloxyethylcarbamate (TSMC);polydimethylsiloxane (PDMS) and PDMS derivatives, such as methacrylateend-capped fluoro-grafted PDMS crosslinker, a methacrylate end-cappedurethane-siloxane copolymer crosslinker, a styrene-capped siloxanepolymer containing polyethylene oxide and polypropylene oxide blocks;and siloxanes containing hydrophilic grafts or amino acid residuegrafts, and siloxanes containing hydrophilic blocks or containing aminoacid residue grafts. The molecular structure of these monomers can bealtered chemically to contain moieties that match amino acid residues orother biological molecules. In cases where the above monomers, whenpolymerized with hydrophilic monomers, a solubilizing cosolvent may beused such as dimethylsulfoxide (DMSO), isopropanol, etc. or aprotecting/deprotecting group strategy.

Crosslinking monomer amounts can be from (0.1 to 40%, moles crosslinkingmonomer/moles all monomers); Functional monomers, 99.9% to 60% (molesfunctional monomer/moles all monomers) with varying relative portions ofmultiple functional monomers; initiator concentration ranging from 0.1to 30 wt %; solvent concentration ranging from 0% to 50 wt % (but nosolvent is preferred); monomer to bio-template ratio (M/T) ranging from0.1 to 5,000, preferably 200 to 1,000, with 950 preferred for theketotifen polymers presented herein, under an nitrogen or airenvironment (in air, the wt % of initiator should be increased above 10wt %.

The ophthalmic drug delivery system also includes a bio-template, thatis drug molecules, prodrugs, protein, amino acid, proteinic drug,oligopeptide, polypeptide, oligonucleotide, ribonucleic acid,deoxyribonucleic acid, antibody, vitamin, or other biologically activecompound. This also includes a drug with an attached bio-template. Thebio-template is preferably bound to the hydrogel matrix through one ormore of electrostatic interactions, hydrogen bonding, hydrophobicinteractions, coordination complexation, and Van der Waals forces.

Bio-templates are preferably weakly bound to a hydrogel matrix throughfunctionalized monomer units, macromer units or oligomer units that areco-polymerized into the hydrogel matrix to form receptor locationswithin the hydrogel matrix that resemble or mimic the receptor sites ormolecules associated with the biological target tissue to be treatedwith the drug or the biological mechanism of action.

In accordance with the embodiments of the invention, a portion of thebio-template can be washed out from the recognitive hydrogel polymer,loaded with a drug. The polymerization reaction forms a contact lens.For example, the gel is polymerized in a mold or compression casting.After contact lenses are formed they can be used to administer the drugthrough contact with eyes. Alternatively, the recognitive hydrogelpolymer can be formed into contact lenses, washed to remove a portion ofthe bio-template and then loaded with the drug. Where the bio-templateis the drug, the washing step can be illuminated or truncated. The drugrelease from the lenses can work without washing the drug out andreloading the drug. This is true for cases where the reaction iscomplete and no small monomers are released from the structure. Informulations where the bio-template is a drug, the free base form of thedrug or hydrochloride salt of the drug can be used.

In accordance with the method of the present invention, a biomimeticrecognitive polymeric hydrogel is formed by making a mixture or solutionthat includes amounts of a bio-template or drug, functionalized monomeror monomers, cross-linking monomer or monomers and polymerizationinitiator in a suitable solvent or without solvent. Suitable initiatorsinclude water and non-water soluble initiators, but are not limited toazobisisobutyronitrile (AIBN), 2,2-dimethoxy-2-phenyl acetophenone(DMPA), 1-hydroxycyclohexyl phenyl ketone (IrgacureÒ 184),2,2-dimethoxy-1,2-diphenylethan-1-one (Irgacure 651), ammoniumpersulfate, iniferter such as tetraethylthiuram disulfide, orcombinations thereof. The polymerization can be photo-initiated,thermally-initiated, redox-initiated or a combinations thereof.

The functionalized monomer or monomers complex with the bio-template andcopolymerize with cross-linking monomer or monomers to form a biomimeticrecognitive polymeric hydrogel, such as described above. Functional orreactive monomers useful herein are those which possess chemical orthermodynamic compatibility with a desired bio-template. As used herein,the term functional monomer includes moieties or chemical compounds inwhich there is at least one double bond group that can be incorporatedinto a growing polymer chain by chemical reaction and one end that hasfunctionality that will interact with the bio-template through one ormore of electrostatic interactions, hydrogen bonding, hydrophobicinteractions, coordination complexation, and Van der Waals forces.Functional monomers includes macromers, oligomers, and polymer chainswith pendent functionality and which have the capability of beingcrosslinked to create the recognitive hydrogel. Crosslinking monomerincludes chemicals with multiple double bond functionality that can bepolymerized into a polymer network.

Initiator-chain transfer molecules, iniferters, have been used toproduce well controlled block copolymers, polymers of lowpolydispersity, and graft polymers as well as crosslinked polymersystems on surfaces. Of utmost importance is the control over thepolymerization and associated network structure, which depends on thedynamic equilibrium between active and dormant species. Conventionalfree-radical polymerization is highly non-ideal and differences intheory and experimental data indicate heterogeneity within the networkstructure.

In order to control the polymerization reaction further by altering thekinetic chain length and potentially increasing the number ofrecognition sites and the quality of recognition (e.g., alter thestructural architecture of the polymeric network to affect template drugcapacity, affinity, and diffusional transport), we investigated the useof initiator-chain transfer molecules, iniferters. By using theiniferter, tetraethylthiuram disulfide (TED), the number of bindingsites was dramatically increased at approximately equivalent bindingaffinity. Iniferters used in this work decay into two dithiocarbamylradicals (DTC); which are more stable compared to carbon radicals. Thestability of the iniferter produced radical negates its significance onthe initiation and propagation steps during the polymerization reaction,which in this particular case required the addition of carbon radicals,AIBN, to initiate the polymerization reaction. During termination stepsof the polymerization reaction, the stable DTC radicals reversiblyterminate with growing polymer radical chains which forms a chain thatcan re-absorb UV light and decay back into a polymer radical and a DTCradical. The limitations and structural heterogeneity of radicalpolymerizations caused by fast termination reactions can be reducedsince iniferters provide a reversible termination reaction.

Examples of living or controlled polymerization include, but are notlimited to living anioinic or cationic polymerization, ring openingmetathesis polymerization (ROMP), group transfer polymerization (GOP),living Ziegler-Natta polymerization, and free-radical polymerization(e.g., iniferter polymerization, catalytic chain transferpolymerization, stable free radical mediated polymerization (SFRP), ATRFor atom transfer radical polymerization, reversible additionfragmentation chain transfer (RAFT) polymerization, Iodine Transferpolymerization, Selenium-centered mediated polymerization,Telluride-mediated polymerization (TERP), Stibine-mediatedpolymerization).

Examples of functionalized monomers include, but are not limited to,2-hydroxyethylmethacrylate (HEMA), Acrylic Acid (AA), Acrylamide (AM),N-vinyl 2-pyrrolidone (NVP), 1-vinyl-2-pyrrolidone (VP), methylmethacrylate (MMA), methacrylic acid (MAA), acetone acrylamide,2-ethyl-2-(hydroxymethyl)-1,3-propanediol trimethacrylate,N-(1,1-dimethyl-3-oxobutyl)acrylamide,2-ethyl-2-(hydroxymethyl)-1,3-propanediol trimethacrylate,2,3-dihydroxypropyl methacrylate, allyl methacrylate,3-[3,3,5,5,5-pentamethyl-1,1-bis[pentamethyldisiloxanyl)oxy]trisiloxanyl]propylmethacrylate,3-[3,3,3-trimethyl-1,1-bis(trimethylsiloxy)disiloxanyl]propylmethacrylate (TRIS), N-(1,1-dimethyl-3-oxybutyl)acrylamide, dimethylitaconate, 2,2,2,-trifluoro-1-(trifluoromethyl)ethyl methacrylate,2,2,2-trifluoroethyl methacrylate,methacryloxypropylbis(trimethylsiloxy)methylsilane,methacryloxypropylpentamethyldisiloxane,(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane,4-t-butyl-2-hydroxycyclohexyl methacrylate, dimethylacrylamide, glycerolmethacrylate and diethylaminoethyl methacrylate (DEAEM). Functionalizedmonomers herein also includes short or long proteins or nucleic acidssequences. Once formed the biomimetic recognitive polymeric hydrogel canbe formed into contact lenses or, as described above, the polymerizationreaction forms the contact lenses.

In accordance with further embodiments of the invention, functionalizedmonomers are synthesized or selected by identifying receptor sites ormolecules associated with the target biological tissue to be treated bythe drug or that are associated with metabolizing the drug. Next,functionalized portions of the functionalized monomers are synthesizedto chemically and/or structurally resemble or mimic the receptor sitesor molecules that are associated with the biological mechanism of actionof the drug. These functionalized monomers are then copolymerized withthe cross-linking monomer or monomers used to form the hydrogel matrix,such as described above.

After the drug has been depleted from the contact lenses through theeyes, the contact lenses can be re-loaded with the drug by soaking thecontact lenses in the reconstituting drug solution. While the contactlenses have been described in detail as being used to deliverantihistamines and other allergy drugs, ophthalmic drug delivery systemsand methods of the present invention can be used to deliver any numberof drugs through contact on the eye and/or systemically.

Drugs that can be delivered by the system and method of the presentinvention include, but are not limited to, Anti-bacterials,Anti-infectives, Anti-microbial Agents, such as anti-fungal agents (allof which generally referred to as antibiotics) such as Penicillins(including Aminopenicillins and/or penicillinas in conjunction withpenicillinase inhibitor and anti-fungal agents), Cephalosporins (and theclosely related cephamycins and carbapenems), Fluoroquinolones,Tetracyclines, Macrolides, Aminoglycosides. Specific examples include,but are not limited to, erythromycin, bacitracin zinc, polymyxin,polymyxin B sulfates, neomycin, gentamycin, tobramycin, gramicidin,ciprofloxacin, trimethoprim, ofloxacin, levofloxacin, gatifloxacin,moxifloxacin, norfloxacin, sodium sulfacetamide, chloramphenicol,tetracycline, azithromycin, clarithyromycin, trimethoprim sulfate andbacitracin.

The ophthalmic drug delivery system and method of the present inventioncan also be used to deliver Non-steroidal (NSAIDs) and SteroidalAnti-inflammatory Agents (generally referred to as anti-inflammatoryagents) including both COX-1 and COX-2 inhibitors. Examples include, butare not limited to, corticosteroids, medrysone, prednisolone,prednisolone acetate, prednisolone sodium phosphate, fluormetholone,dexamethasone, dexamethasone sodium phosphate, betamethasone,fluoromethasone, antazoline, fluorometholone acetate, rimexolone,loteprednol etabonate, diclofenac (diclofenac sodium), ketorolac,ketorolac tromethamine, hydrocortisone, bromfenac, flurbiprofen,antazoline and xylometazoline.

The ophthalmic drug delivery system and method of the present inventioncan also be used to deliver Anti-histamines, Mast cell stabilizers, andAnti-allergy Agents (generally referred to as anti-histamines). Examplesinclude, but are not limited, cromolyn sodium, lodoxamide tromethamine,olopatadine HCl, nedocromil sodium, ketotifen fumurate, levocabastineHCL, azelastine HCL, pemirolast (pemirolast potassium), epinastine HCL,naphazoline HCL, emedastine, antazoline, pheniramine, sodiumcromoglycate, N-acetyl-aspartyl glutamic acid and amlexanox.

In yet further embodiments of the invention the ophthalmic drug deliverysystem and method are used to deliver Anti-viral Agents including, butnot limited to, trifluridine and vidarabine; Anti-Cancer Therapeuticsincluding, but not limited to, dexamethasone and 5-fluorouracil (5FU);Local Anesthetics including, but not limited to, tetracaine,proparacaine HCL and benoxinate HCL; Cycloplegics and Mydriaticsincluding, but not limited to, Atropine sulfate, phenylephrine HCL,Cyclopentolate HCL, scopolamine HBr, homatropine HBr, tropicamide andhydroxyamphetamine Hbr; Comfort Molecules or Molecules (generallyreferred as lubricating agents) to treat Keratoconjunctivitis Sicca (DryEye) including, but not limited to, Hyaluronic acid or hyaluronan (ofvarying Molecular Weight, MW), hydroxypropyl cellulose (of varying MW),gefarnate, hydroxyeicosatetranenoic acid (15-(S)-HETE),phospholipid-HETE derivatives, phoshoroylcholine or other polar lipids,carboxymethyl cellulose (of varying MW), polyethylene glycol (of varyingMW), polyvinyl alcohol (of varying MW), rebamipide, pimecrolimus, ecabetsodium and hydrophilic polymers; Immuno-suppressive andImmuno-modulating Agents including, but not limited to, Cyclosporine,tacrolimus, anti-IgE and cytokine antagonists; and Anti-Glaucoma Agentsincluding beta blockers, pilocarpine, direct-acting miotics,prostagladins, alpha adrenergic agonists, carbonic anhydrase inhibitorsincluding, but not limited to betaxolol HCL, levobunolol HCL,metipranolol HCL, timolol maleate or hemihydrate, carteolol HCL,carbachol, pilocarpine HCL, latanoprost, bimatoprost, travoprost,brimonidine tartrate, apraclonidine HCL, brinzolamide and dorzolamideHCL; decongestants, vasodilaters vasoconstrictors including, but notlimited to epinephrine and pseudoephedrine.

In yet further embodiments of the invention the ophthalmic drug deliverysystem and method are used to deliver anti-microbial agents including,but not limited to, anti-fungal agents. A number of different classes ofanti-microbial or anti-fugal agents are considered to be within thescope of the present invention. Suitable classes of anti-microbial oranti-fugal agents include, but are not limited to, Allyamines, othernon-azole ergosterol biosynthesis inhibitors, antimetabolities, Azoles,Chitin Synthase Inhibitors, Glucan Synthesis Inhibitors, and Polyenes.

Examples of Allyamines include, but are not limited to, Amorolfine,Butenafine, Naftifine and Terbinafine; an example of an antimetaboliteincludes, but is not limited to, Flucytosine; examples of Azolesinclude, but are not limited to, Imadazoles and Triazoles, such asFluconazole, Itraconazole, Ketoconazole, Posaconazole, Ravuconazole,Voriconazole, Clotrimazole, Econazole, Miconazole, Miconazole Nitrate,Oxiconazole, Sulconazole, Terconazole, Tioconazole and Enilconazole;examples of Chitin Synthase Inhibitors include, but are not limited to,Nikkomycin Z and Lufenuron; examples of Echinocandins or GlucanSynthesis Inhibitors include, but are not limited to, Caspofungin,Micafugin and Anidulafungin, examples of Polyenes include, but are notlimited to, Amphotericin B (AmB), Natamycin, Pimaricinand Nystatin.Other suiatbel anti-microbial or anti-fugal agents include, but are notlimited to, Chlorhexidine gluconate, Griseofulvin, Ciclopirox Olamine,Haloprogin, Tolnaftate, Undecylenate, Povidone iodine, Silversulfadiazine and antimicrobial peptides and glycoproteins (e.g., such aslactoferrin, ambicin, nisin, polymixin B, gramicidin S, etc.).

An ophthalmic drug delivery system of the present invention hasparticular applications for treating animals, including large animalssuch as horses diagnosed with equine fungal keratitis with ananti-microbial agents or anti-fungal agents such as those listed above.Equine fungal keratitis is a corneal disease that accounts for 13% ofall equine corneal problems. It is generally caused by corneal trauma,usually associated with injury by organic matter. The injury allowsfungal microorganisms to invade the cornea and cause ulcers, anterioruvetis, corneal perforation and iris prolapse. The typical treatment forequine fungal keratitis is frequent, expensive and prolonged treatment.This is due to the number of ocular treatment barriers and thedifficulty of dealing with large animals.

For example, a single drop of topical ointment (the usual topical dose)has a residence time of between 2-23 minutes. As a result, thebioavailability of the drug is approximately 10% of the administereddose. About 44% of animals diagnosed with equine fungal keratitis goblind and a number of these cases require that the eye is removed toprevent further spreading of infection.

The physiological properties of the eye hinder the effectiveness oftopical ocular drugs. Because of the effectiveness of the tear film influshing out foreign substances, the goal of this novel ocular drugdelivery method is to increase the bioavailibility by releasing asmaller concentration of the drug at a constant rate, thereby increasingthe corneal contact time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing the steps for making contact lenses, inaccordance with the embodiments of the invention.

FIG. 2 illustrates the formation of a recognitive polymeric hydrogel, inaccordance with the embodiments of the invention.

FIG. 3 is a flow chart of outlining steps for making functionalizedmonomer used in the synthesis of recognitive polymeric hydrogels, inaccordance with the embodiments of the invention.

FIGS. 4A-C illustrate examples of sets of molecules that match, resembleor mimic each other.

FIGS. 5A-B are graphs that compare Ketotifen equilibrium isotherms inwater for a recognitive polymeric hydrogel and a control hydrogel.

FIG. 5C is a graph of drug loading for recognitive polymeric hydrogelsof the present invention against control hydrogels to show the enhanceddrug loading for recognitive polymeric hydrogels of the presentinvention.

FIG. 6 is a graph of drug release profiles for therapeutic contactlenses, in accordance with the embodiments of the invention.

FIGS. 7A-B are graphs of drug release profiles for recognitive polymerichydrogels, in accordance with the embodiments of the invention.

FIG. 8 is a graph that compares fluconazale with the fungal cytochromeP450 equilibrium isotherms in water for a recognitive polymeric hydrogeland a control hydrogel.

FIG. 9 shows Fluconazole binding isotherm of 5% crosslinkedpoly-HEMA-co-AM-co-DEAEM-co-NVP-co-PEG200DMA hydrogel lenses (N=3, T=25C). Percentage denotes percent mole crosslinker per mole total monomersin feed.

FIG. 10 shows Fluconazole dynamic release in artificial lacrimalsolution from 5% crosslinkedpoly-HEMA-co-AM-co-DEAEM-co-NVP-co-PEG200DMA hydrogel lenses (N=3, T=25C). Percentage denotes percent mole crosslinker per mole total monomersin feed.

FIG. 11 illustrates drug loading differences between free radialpolymerization and living polymerization and iniferter reactionstrategies.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Hydrogels are insoluble, cross-linked polymer network structurescomposed of hydrophilic homo- or hetero-co-polymers, which have theability to absorb significant amounts of water. Consequently, this is anessential property to achieve an immunotolerant surface and matrix(i.e., with respect to protein adsorption or cell adhesion). Due totheir significant water content, hydrogels also possess a degree offlexibility very similar to that of natural tissue, which minimizespotential irritation to surrounding membranes and tissues.

The hydrophilic and hydrophobic balance of a gel carrier can be alteredto provide tunable contributions that present different solventdiffusion characteristics, which in turn influence the diffusive releaseof a drug contained within the gel matrix. In general, one maypolymerize a hydrophilic monomer with other less hydrophilic or morehydrophobic monomers to achieve desired swelling properties.

These techniques have led to a wide range of swellable hydrogels.Knowledge of the swelling characteristics is of major importance inbiomedical and pharmaceutical applications since the equilibrium degreeof swelling influences the diffusion coefficient through the hydrogel,surface properties and surface mobility, mechanical properties, andoptical properties. Drug release depends on two simultaneous rateprocesses: water migration into the network and drug diffusion outwardthrough the swollen gel.

Soft contact lenses are made of hydrogels. Contact lenses aremanufactured to have a number of characteristics such as optical quality(good transmission of visible light), high chemical and mechanicalstability, manufacturability at reasonable cost, high oxygentransmissibility, tear film wettability for comfort, and resistance toaccumulation of protein and lipid deposits, as well as a suitablecleaning and disinfecting scheme.

Soft contact lenses typically consist of poly(2-hydroxyethylmethacrylate) (PHEMA). Other lens materials include HEMA copolymerizedwith other monomers such as methacrylic acid, acetone acrylamide, andvinyl pyrrolidone. Also, commonly used materials include copolymers ofvinyl pyrrolidone and methyl methacrylate as well as copolymers ofglycerol methacrylate and methyl methacrylate.

Minor ingredients have included a variety of other monomers as well ascross-linking agents.

The immersion and soaking of soft contact lenses in drug solutions hasshown promise in the increase of drug bioavailability with a reductionof side effects. However, the materials and constituent chemistry of themacromolecular chains and subsequent interaction with drugs is randomand typically leads to poor drug loading.

In order to address the above referenced shortcomings, the presentinvention is directed to the use of biomimetic imprinting of hydrogelsto make hydrogel matrices that can selectively bind a drug throughcomplexing sites leading to improved loading of a drug and controlledtime release of the drug. These hydrogels are referred to as recognitivepolymeric hydrogels. The polymerization reaction forms the contactlenses, which can be used to administer drugs through contact with theeyes, thereby replacing traditional eye drop therapies. Alternatively,the recognitive polymeric hydrogels can be formed or fashioned intocontact lenses which can be used to administer drugs through contactwith the eyes, thereby replacing traditional eye drop therapies or othermechanisms of delivery.

For example, ketotifen fumurate is a potent fast acting and highlyselective histamine H1 antagonists with a sustained duration of action.Levocabastine and ketotifen fumurate inhibits itching, redness, eyelidswelling, tearing, and chemosis induced by conjunctival provocation withallergens and histamine. With topical application in the form of eyedrops, absorption is incomplete and bioavailability is low. Thus, thedose is usually administered multiple times daily. Also, due to a highconcentration of drug and other constituents of the ophthalmicsuspension preparation, patients are advised not to wear soft contactlenses. Accordingly, a soft contact lens used to administer ketotifenfumurate would not only enhance the efficacy of the treatment, but alsoallow allergy sufferers to wear contact lenses.

FIG. 1 is a flow chart 100 of steps for making contact lenses, inaccordance with the embodiments of the invention, and FIG. 2 is agraphical representation of forming a recognitive polymeric hydrogelmatrix 221. Referring to FIG. 1 and FIG. 2 in the step 101, therecognitive hydrogel set 221 is formed. The recognitive hydrogel matrix221 is formed by generating a solution 200 comprising one or morebio-template 201, one or more functionalized monomers 203 and 203′, oneor more cross-linking monomers 205 with or without a solvent. In thesolution 200 the functionalized monomers 203 and 203′ complexes with thebio-templates 201. A suitable initiator or mixture initiators 207 areused to co-polymerize the functionalized monomers 203 and 203′ with across-linking monomer 205 to form a loaded hydrogel 220 comprising ahydrogel matrix 221 with bio-templates 201 complexing at site 209through the hydrogel matrix 221.

Preferably, the bio-templates 201 are complexed with the hydrogel matrix221 through weak or non-covalent interactions, as explained above,whereby the bio-templates 201 can be washed or rinsed from the loadedhydrogel 220 to form an hydrogel matrix 221, which has vacant complexingsites 209 that can be used to complex drug molecules that arestructurally and/or chemically similar to the bio-templates 201. It willbe clear from the discussions above and below that the bio-templates 201can be a drug and, therefore, washing the bio-templates 201 from thehydrogel matrix 221 may not be necessary for all drug delivery systemsthat are synthesized.

Still referring to both FIG. 1 and FIG. 2, after the hydrogel matrix 221is formed, in the step 101, in the step 103 the hydrogel matrix 221 canbe formed into contact lenses using any technique known in the art. Itis understood that the step the step 103 is not necessary when thepolymerization reaction forms the contact lenses, such as describedpreviously. Where the bio-template 201 is a drug, the contact lenses canbe placed in contact with eyes in the step 107 to administer or deliverthe drug to or through the eyes. Where the bio-template 201 has beenwashed from the recognitive hydrogel matrix prior to or after the step103 of forming the contact lenses from the recognitive hydrogel matrix,then in the step 109 or the step 105, respectively, the recognitivehydrogel matrix or the contact lenses are loaded with a drug. Therecognitive hydrogel matrix or the contact lenses can be loaded with thedrug by soaking the recognitive hydrogel matrix or the contact lenses inan aqueous drug solution.

Now referring to FIG. 2 and FIG. 3, in accordance with furtherembodiments of the invention prior to the step of making an ophthalmicdrug delivery system, such as described with reference to FIG. 1, in thestep 301 the target tissue to be treated with the drug or biologicalmechanism of action is studied to determine the types of molecules orfunctional groups that are associated with the action of the drug at thetarget tissue to affect the target tissue. Based on this information, inthe step 303, functionalized monomers are synthesized with functionalgroups that mimic or resemble molecules or functional groups that areassociated with the action of the drug at the target tissue. Next, inthe step 100, the functionalized monomers with the functional groupsthat mimic or resemble molecules or functional groups that areassociated with metabolizing the drug at the target tissue are then usedto synthesize a drug delivery system, such as described above withreference to FIG. 1. The biomimetic approach is the processes ofmimicking biological recognition or exploiting biological mechanisms.Specifically, it is the process of coordinating biological molecularrecognition, interactions, or actions to design materials that can bestructurally similar to and/or function in similar ways as biologicalstructures.

FIGS. 4A-C illustrate examples of sets of molecules that match, resembleor mimic each other. With reference to the bio-mimetic approach forsynthesizing recognitive hydrogel polymers described above, acrylic acidcan be used to mimic aspartic acid (FIG. 4A), acrylaminde can be used tomimic asparagine (FIG. 4B) and N-vinyl pyrrolidinone can be used tomimic tyrosine (FIG. 4C). Aspartic acid, asparagine, and tyrosine areknown to be of the group of amino acids providing the non-covalentinteractions in the ligand binding pocket for histamine. For example,structural analysis of ligand binding pockets and amino acids involvedin multiple non-covalent binding points provide one of many rationalframeworks to synthesize recognitive networks from functional monomers.Antihistamine has been shown to bind more tightly and have a higheraffinity than histamine for the histamine binding pocket.

EXAMPLE

Materials and Methods: Acrylic Acid (AA), Acrylamide (AM),N-Vinyl-2-Pyrrolidone (NVP) and 2-hydroxyethylmethacrylate (HEMA),Azobisisobutyronitrile (AIBN), and Ketotifen Fumarate were purchasedfrom Sigma-Aldrich. Polyethylene glycol (200) dimethacrylate (PEG200DMA)was purchased from Polysciences, Inc. All chemicals were used asreceived. Polymer and copolymer networks were made using variousmixtures of above monomers (e.g. Poly(AA-co-AM-HEMA-PEG200DMA), Poly(AA-co-HEMA-co-PEG200DMA), Poly (AM-co-HEMA-co-PEG200DMA),Poly(AA-co-AM-co-NVP-co-HEMA-PEG200DMA)). Current work is directed toproducing networks that can also be used in the formation of contactlens for anti-histamines with monomers and copolymers of molecules suchas N-vinyl 2-pyrrolidone (NVP), 1-vinyl-2-pyrrolidone (VP), methylmethacrylate (MMA), methacrylic acid (MAA), acetone acrylamide, ethyleneglycol dimethacrylate (EGDMA), 2-ethyl-2-(hydroxymethyl)-1,3-propanedioltrimethacrylate, N-(1,1-dimethyl-3-oxobutyl)acrylamide,2-ethyl-2-(hydroxymethyl)-1,3-propanediol trimethacrylate,2,3-dihydroxypropyl methacrylate, allyl methacrylate any other suitablemonomers, such as those referenced previously.

Accurate quantities of monomers, template molecules and crosslinkerswere added in that order, and the mixture was sonicated to obtain ahomogenous solution. In particular, a typical formulation consisted of 5mole % cross-linking monomer (PEG200DMA) in a solution of Acrylamide(M), HEMA (M), Ketotifen (T), with an M/T ratio of approximately 950(92% HEMA, 1% of remaining monomers, and approximately 1 mole % drugdepending on the M/T ratio). Controls were also prepared without thetemplate. Next, initiator AIBN was added in low light conditions, andthe solutions were allowed to equilibrate for 12 hours in darkness. Thisstep allowed the monomers and template to orient them selves and reachtheir free energy minima, thus beginning the configurational imprintingat the molecular level. However, this step occurs very quickly, such ason the order of minutes.

The solutions were then transferred to an MBRAUN Labmaster 130 1500/1000Glovebox, which provides an inert nitrogenous and temperature-controlledatmosphere for free-radical photopolymerization. With an increase inphotoinitiator wt. %, this step can proceed in air. The solutions wereuncapped and left open to the nitrogen until the oxygen levels reachednegligible levels (<0.1 ppm). The solutions were inserted into glassmolds (6 in. by 6 in.) separated by a Teflon frame 0.8 mm wide, asmeasured by a Vernier caliper. The glass plates were coated withchlorotrimethylsilane to prevent the polymer matrix from sticking to theglass, as it demonstrates a strong adherent tendency due to hydrogenbonding.

Polymerization was carried out for ten minutes at 325 V using a Dymax UV(ultra-violet) light source. The intensity of radiation was 40 mW/cm²,as measured with a radiometer, and the temperature was 36° C., asmeasured with a thermocouple.

The polymer was peeled off the glass plates with flowing deionized water(Millipore, 18.2 mO.cm, pH 6), and then was allowed to soften forapproximately 10 minutes. Circular discs were cut using a Size 10 corkborer (13.5 mm), and were typically washed for 5 days in a continuousflow system using deionized water. All washes proceeded until theabsence of detectable drug was verified by spectroscopic monitoring. Toobtain dry weights, some discs were allowed to dry under laboratoryconditions (20° C.) for 36 hours. The discs were then transferred to avacuum oven (27 in. Hg, 33-34° C.) for 48 hours until they were dry(less than 0.1 wt % difference).

Polymer penetrant uptake and swelling data were obtained in deionizedwater with samples taken every 5 min. for the first hour, and then everyhour for 10 hours until equilibrium was reached. As the gel was removedfrom the water, excess surface water was dabbed with a dry Kim wipe. Theequilibrium weight swelling ratio at time t, q, for a given gel wascalculated using the weights of the gels at a time and the dry polymerweights, respectively, using equations based on the Archimedes principleof buoyancy. Dynamic and Equilibrium Template Binding: Dynamic templatedrug molecule binding was performed until equilibrium had beenestablished for each system. Stock solutions of drug with aconcentration 2 mg/ml were prepared and diluted with deionized water toproduce 0.1, 0.2, 0.3, 0.4 and 0.5 mg/ml solutions. Each solution wasvortexed for 30 seconds to provide homogeneity, and initial UVabsorbances were noted. Gels were then inserted into the vials and wereplaced on a Stovall Belly Button Orbital Shaker over the entire durationof the binding cycle to provide adequate mixing. A 200 μL aliquot ofeach sample was placed in a Corning Costar UV-transparent microplate,and absorbance readings were taken using a Biotek Spectrophotometer at268 nm. After measurement, the read sample was returned to the originalbatch, to avoid fluctuations in concentrations due to sampling methods.

Dynamic Release Studies: In obtaining the preliminary results, dynamicrelease studies were conducted in DI water, artificial lacrimal fluid(6.78 g/L NaCl, 2.18 g/L NaHCO₃, 1.38 g/L KCl, 0.084 g/L CaCl₂, 2H₂O, pH8), and lysozyme (1 mg/ml) in artificial lacrimal fluid. Gels which hadbeen drug loaded were placed in 30 ml of DI water, and the solutionswere continuously agitated with a Servodyne mixer (Cole PalmerInstrument Co.) at 120 rpm. Release of drug was monitored at 268 nm bydrawing 200 μL of solution into a 96-well Corning Costar UV-transparentmicroplate, and measurements were taken in a Synergy UV-VisSpectrophotometer (Biotek). Absorbances were recorded for three samples,averaged, and corrected by subtracting the relevant controls. Solutionswere replaced after each reading. Separate studies were conducted todetermine if infinite sink conditions existed and those conditions werematched throughout all experiments.

Polymerization Kinetics and Network Formation: Solutions were preparedwith 0, 0.1, 0.5, and 1 mole percent of Ketotifen in the initial monomersolutions. Kinetic studies were conducted with a differential scanningphotocalorimeter (DPC, Model No. DSC Q100, TA Instruments with Mercurylight source). Samples of 10 μL were placed in an aluminum hermetic panand purged with nitrogen (flow rate 40 ml/min) in order to preventoxidative inhibition. The solution was allowed to equilibrate at 35° C.for 15 minutes, before being exposed to UV light at 40 mW/cm2 for 12minutes.

The heat that radiated was measured as a function of time, and thetheoretical enthalpy of the monomer solution was used to calculate therate of polymerization, Rp, in units of fractional double bondconversion per second. Integration of the rate of polymerization curveversus time yielded the conversion as a function of time reaction rate.The presence of template and a solvent, if used, was accounted for inthe calculations, as it did not participate in the polymerizationreaction. Experimental results were reproducible and the greatest sourceof error involved the assumed theoretical enthalpies in the calculationsof the rate of polymerization and conversion. For all studies, theenthalpies were assumed to have errors of +5%. The assumptions in thecopolymerization of two monomers (i.e., functional and cross-linkingmonomers) were that each monomer had equal reactivity and thetheoretical enthalpy derived for a co-monomer mixture was an average ofthe enthalpies of individual monomers. The theoretical enthalpy ofmethacrylate double bonds was equal to 13.1 kcal mole-1 and thetheoretical enthalpy of acrylate double bonds was equal to 20.6 kcalmole-1.

Results

FIG. 5A shows a graph 500 of the equilibrium binding isotherm forKetotifen in water for Poly(acrylamide-co-HEMA-co-poly(ethyleneglycol)200 dimethacrylate) hydrogel networks with a cross-linkingpercentage of 5%. N=3 and T=25° C. The recognitive hydrogel network isrepresented by the line 501 and the control hydrogel network isrepresented by the line 503. Percentage denotes percent mole crosslinkerper mole total monomers in feed.

FIG. 5B shows a graph 510 of the equilibrium binding isotherm forKetotifen in water for Poly(acrylic acid-co-HEMA-co-poly(ethyleneglycol)200 dimethacrylate) hydrogel networks with a cross-linkingpercentage of 5%. N=3 and T=25° C. The recognitive hydrogel networks isrepresented by the line 511 and the control hydrogel network isrepresented by the line 513. Percentage denotes percent mole crosslinkerper mole total monomers in feed.

FIG. 5C shows a graph 540 of enhanced Loading of Ketotifen for MultipleMonomer Gels for Poly(n-co-HEMA-co-poly(ethylene glycol)200dimethacrylate) Networks. The Functional monomers use are acrylic acid,acrylamide, NVP, or an equal mole mixture of both. The Recognitivenetworks are shown as hatched bars 543 and the Control networks areshown as clear bars 541.

FIG. 6 shows a graph 600 of Tailorable Release Profiles Of TherapeuticContact Lenses for Poly(n-co-HEMA-co-poly(ethylene glycol)200dimethacrylate) Networks in Artificial Lacrimal Fluid, where n is AM(represented by circles), AA (represented by squares), AA-AM(represented by triangles), and NVP-AA-AM (represented by diamonds)recognitive networks, respectively. Results demonstrate an approximatelyconstant release rate of ketotifen fumurate for 1 to 5 days.

FIG. 7A shows a graph 700 of Release Data forPoly(AM-co-HEMA-co-poly(ethyleneglycol)200 dimethacrylate) RecognitiveNetworks. Fraction of Mass Released in Artificial Lacrimal SolutionWith/Without Lysozyme.

FIG. 7B shows a graph 725 of Release Data forPoly(AM-co-AA-co-HEMA-co-poly(ethyleneglycol)200 dimethacrylate)Networks Mass of Drug Released in Artificial Lacrimal Solution.

FIG. 8 shows a graph 800 of the equilibrium binding isotherm forfluconazale with the fungal cytochrome P450 in water for Poly(acrylicacid-co-HEMA-co-poly(ethylene glycol)200 dimethacrylate) hydrogelnetworks with a cross-linking percentage of 5%. N=3 and T=25° C. Therecognitive hydrogel network is represented by the line 811 and thecontrol hydrogel network is represented by the line 813. Percentagedenotes percent mole crosslinker per mole total monomers in feed.

I. Enhanced Loading and Performance of Multiple Monomer Mixtures

In the preliminary work, hydrogels were produced with enhanced loadingfor ketotifen fumarate. Polymers were made with the following monomers:acrylic acid (AA), N-vinyl 2-pyrrolidone (NVP), acrylamide (AM),2-hydroxyethylmethacrylate (HEMA), and polyethylene glycol (200)dimethacrylate (PEG200DMA).

We hypothesized that gels composed of multiple functional monomers wouldoutperform those composed of single functional monomers. Foranti-histamine recognitive polymers, this would better mimic the dockingsite of histamine at the molecular level providing all the relevantfunctionality necessary for non-covalent interactions. We have provedthat loading properties of gels are improved with multiple monomermixtures.

Gels of multiple complexation points with varying functionalitiesoutperformed the gels formed with less diverse functional monomers andshowed the highest maximum bond of ketotifen and highest difference overcontrol gels. Equilibrium binding isotherms forPoly(AM-co-AA-co-HEMA-co-PEG200DMA) networks demonstrate enhancedloading with a factor of 2 times increase in the loading of drugcompared to conventional networks (i.e., gels prepared without templateand comparable to existing contact lenses) depending on polymerformulation and polymerization conditions. Poly(AM-co-HEMA-co-PEG200DMA)networks demonstrated a factor of 2 or 100% increase in the loading ofdrug compared to control networks with lower bond amounts.Poly(AA-co-HEMA-co-PEG200DMA) networks show a factor of 6 times increaseover control in the loading of ketotifen with the overall drug boundbeing the lowest of the polymer formulation studies (approximately 33%less ketotifen loading than the AM functionalized network).

For all systems, an increase in the amount of loaded drug has beenconfirmed, but with the most biomimetic formulation(Poly(AA-co-AM-co-NVP-co-HEMA-PEG200DMA)) a significant increase inloading is demonstrated yielding the greatest loading potential (thehighest loading achieved to date and 6× over control networks due tomultiple binding points with varying functionalities) (FIG. 5C).

II. Dynamic Drug Release Profiles

Dynamic release profiles in artificial lacrimal solution and anartificial lacrimal solution with protein, demonstrated extended releaseof a viable therapeutic concentration of ketotifen. Release studiesconfirmed that release rates can be tailored via type and amount offunctionality and extended from one to five days. FIG. 6 highlightsnormalized data of the fraction of drug released versus time (massdelivered at time t divided by the mass delivered at infinite time). Forpoly(n-co-HEMA-co-PEG200DMA) networks (where n was AA-co-AM, AM, or AA),the release of drug showed a relatively constant rate of release forapproximately 1 day, with little difference in the release profile.However, the most structurally biomimetic network,poly(AA-co-AM-co-NVP-co-HEMA-PEG200DMA), exhibited a five fold increasein the extended release profile (i.e., approximately 5 days).

It is hypothesized that providing all the relevant functionality to themimicked docking site with the proposed polymer synthesis techniqueaffords a higher affinity of the drug for the network and thus an evenslower release of drug compared to control networks. Furthermore, a fiveto seven day release profile fits quite well into the time usage ofone-week extended-wear soft contact lenses.

It has been demonstrated that the loading of drug can be controlled bythe type, number, and diversity of functionality within the network. Theloading (and hence the mass delivery) can also be controlled by theinitial loading concentration of the drug. We have demonstrated controlover the cumulative mass of drug released by changing the loadingconcentration. By considering the relative size of our gels (e.g., gelswere slightly bigger than normal lenses) and mass of drug released incomparison to typical ophthalmic eye drop dosages (ketotifen 0.25 mg/mLof solution with one drop every 8 hours), the preliminary resultsrevealed that a therapeutically relevant dosage could be delivered forextended periods of time.

To investigate the effect of protein on dynamic release, we choselysozyme as a model protein since it is the largest protein component intear fluid. FIGS. 7A-B highlight the poly(AM-co-HEMA-co-PEG200DMA)network release profile in artificial lacrimal solution with lysozyme,which leads to a factor of 5 increase in the duration of release. Forthe most structurally biomimetic network,poly(AA-co-AM-co-NVP-co-HEMA-PEG200DMA), this could lead to a sustainedrelease approaching 25 days. These studies demonstrate that the time ofrelease may be delayed even further in an in vivo environment, leadingto a substantial increase in applicability of contact lens oculardelivery.

III. Polymerization Reaction Analysis

The rate of polymerization for a given conversion decreased forincreasing mole percentage of template molecule in pre-polymerizationmonomer solution. Thus, the formation of polymer chains and the enhancedloading due to the configurational biomimetic effect may be related tothe propagation of polymer chains. The template molecule poses physicalconstraints to free radical and propagating chain motion and henceeffectively lowers the rate of polymerization in the creation of ligandbinding pockets. These results show that CBIP is reflected at themolecular level. For a given conversion, the rate of polymerization waslower for the multiple functional monomer pre-polymerization mixturesthan the single monomer mixtures. We hypothesize that CBIP with multiplemonomers results in the formation of better ligand-binding pockets withenhanced loading properties which leads to slower rates ofpolymerization.

IV. Equilibrium Swelling Profiles and Mechanical Property Analysis:

Equilibrium swelling studies in DI water and 0.5 mg/ml concentratedketotifen solution indicated that recognitive and control networks werestatistically the same and that 40% of the swollen gels is water, astatistic that indicates a quality that the comfort of wearing and theoxygen permeability of these gels is in agreement with conventionalcontact lenses. These studies indicated that CBIP, and not an increasedporosity or surface area of the gel, is responsible for the enhancedloading properties. It also demonstrated that the loading process doesnot affect the rate of swelling of the polymer matrix.

Further studies on the mechanical properties of the gels have shownstorage and loss moduli, glass transition temperatures and dampingfactors comparable to those of conventional contact lenses (data notshown). Each gel produced was optically clear and had sufficientviscoelasticity to be molded into thin films for refractive differences.

V. Synthesis of Fluconazole Recognitive Networks:

The functional monomers were selected by analyzing the binding mechanismof fluconzale with that of fungal cytochrome P450. The functionalmonomers chosen were n-vinyl pyrrolidone (NVP) hydroxyethyl methacrylate(HEMA) diethylaminoethyl methacrylate (DEAEM), and acrylamide (AM). Thecrosslinking monomer was polyethylene glycol dimethacrylate (PEG200DMA)and the initiator for the polymerization reaction wasazobisisobutyronitrile, AIBN. Crosslinker monomer, functional monomer,and templates were placed in an amber bottle and allowed to equilibratein a light-controlled location. The initiator was added after themonomers and template were completely mixed. The solutions were mixedand used within 24 hours. The control and sample solutions were added toa template between two glass plates, and polymerized using UVpolymerization in a nitrogen environment. The gels were washed and cutinto uniform disks with a 10 mm cork borer. Binding studies wereperformed by placing washed gels into solutions of incremental drugconcentrations and recording absorbance after equilibration to determinethe amount of drug bound. Release studies were performed by placing thedrug-laden gel into a lacrimal solution and taking absorbance readingsat regular intervals to determine the release file.

Fluconazole belongs to the azole class of antifungals and works bybinding with the fungal cytochrome p45 lanosterol 14a-demethylase toinhibit fungal cell wall growth. By analyzing the Mycobacteriumtuberculosis P450 CYP121-fluconazole complex, hydrogen bonding isprovided by Threonine, Serine, and Glutamine residues with hydrophobicinteractions from Valine, Phenylalanine, and Methionine.

FIG. 9 shows a graph 900 of a Fluconazole binding isotherm of 5%crosslinked poly-HEMA-co-AM-co-DEAEM-co-NVP-co-PEG200DMA hydrogellenses. The recognitive hydrogel network is represented by the line 911and the control hydrogel network is represented by the line 913. FIG. 10shows a graph 1000 of Fluconazole dynamic release represented by theline 1001 in artificial lacrimal solution from 5% crosslinkedpoly-HEMA-co-AM-co-DEAEM-co-NVP-co-PEG200DMA hydrogel lenses.

VI. Forming a Living Polymer for Enhanced Drug Loading and Delay DrugTransport:

FIG. 11 illustrates a graph 1100 representing drug loading differencesbetween free radial polymerization and living polymerization andiniferter reaction strategies. The control polymer network isrepresented by the line 1113, the recognitive polymer network isrepresented by the line 1111 and the living polymer network isrepresented by the line 1115. A typical polymerization solutionresulting in polymer designated as Recognitive Gel (FIG. 11), was madewith 0.187 mL ethylene glycol dimethacrylate or EGDMA (0.993 mmole),0.16 mL methacrylic acid or MAA (18.86 mmoles), 18.55 mg ofazo-bis(isobutyronitrile) or AIBN, and 84.06 mg of EA9A template (ethyladenine-9-acetate (EA9A)). Solutions were placed in a sonicator forseveral minutes until all solids were dissolved. The Control Gelsolution was made with exactly the same formulation except no EA9Atemplate was added. The polymer Recognitive Gel (Iniferter) was made byaddition of iniferter, 3.89 mg TED. The molar ratio of the initiator tothe iniferter in Recognitive Gel (Iniferter) was 8.61 with 0.187 mLethylene glycol dimethacrylate or EGDMA (0.993 mmole), 0.16 mLmethacrylic acid or MAA (18.86 mmoles), 18.55 mg ofazo-bis(isobutyronitrile) or AIBN, and 84.06 mg of EA9A template. Inthese gels, the molar ratio of the initiator to the iniferter gavedouble bond conversions similar to the double bond conversions for theRecognitive Gel. For polymerization, the temperature of polymerizationwas (14° C.+/−1° C. throughout exothermic reaction). The molar ratio ofinitiator to iniferter can range 0.0001 and upward.

CONCLUSION

Polymerization kinetics in the presence of the template revealmechanisms of interaction as well as provide criteria with which othertemplate-monomer systems can be chosen experimentally. The use of abiomimetic approach for synthesizing recognitive hydrogel polymers hasled to the development of an ophthalmic drug delivery system usingcontact lenses formed from the recognitive hydrogel polymer. Theophthalmic drug delivery system of the present invention can provideimproved bioavailability and efficacy of drug delivery and exhibitscontrolled time release of the drug. The ophthalmic drug delivery systemcan be tailored to exhibit properties suitable for the intended drugtherapy and has a potential to replace traditional eye drop therapiesand other methods.

This technology creates a new architecture in polymeric films to enableenhanced drug loading and delayed time release of drugs. We have appliedthis to contact lenses to produce a new drug delivery system comprisingcontact lenses. These polymeric films are based on the creation ofpolymeric networks from a fundamental analysis of the biologicalrecognition or biological mechanism of action of the therapeutic. Thetechnologies produced from this work involve thin films for drugdelivery, which can be applied to other areas besides the ocular market.This can apply to, but is not limited to any drug delivery device orcoating where one is limited on space or volume of delivery device. Itcan apply, but is not limited to particles, cylinders, spheres, filmsand coatings.

Areas where this technology is applicable include, but are not limitedto: Refractive and Non-refractive (Cosmetic) Contact Lenses and OcularImplant Devices; Bandage Contact Lenses—Refractive and Non-refractive(Cosmetic) Contact Lenses—that are placed after major or minor eyesurgery to release medication during the healing process and/or aid inocular health;

Nasal Drug Delivery via Ocular Lenses or Devices; Implant Coatings(Orthopedic, Adhesion prevention, etc.); Cardiovascular Device and StentCoatings with Drug Release; Transdermal Patches and Drug Delivery Films;Tissue Engineering and Regeneration Materials (including in vitro);Bandages, Wound Healing; Tissue Regeneration Materials; and Drug TabletCoatings.

The technology also provides an opportunity for a combination drugplatform where multiple drugs are released from a single lens of film.In some cases, multiple drugs of a certain type (combination anti-fungaltherapy) and multiple classes of drugs (anti-inflammatory andantibiotic) are released to achieve more convenient and efficacioustherapy.

The systems of the present invention lead to delayed transport innon-swellable (which is what lenses are) but they may affect swellablehydrogel networks in a similar manner. It is believed that in the systemof the present invention that a multiplicity of the interactions(multiple functional monomers) is preferred for optimal sustainedrelease of a drug.

The present invention has been described in terms of specificembodiments incorporating details to facilitate the understanding of theprinciples of construction and operation of the invention. Suchreference herein to specific embodiments and details thereof is notintended to limit the scope of the claims appended hereto. It will beapparent to those skilled in the art that modifications can be made inthe embodiments chosen for illustration without departing from thespirit and scope of the invention. Specifically, it will be apparent toone of ordinary skill in the art that the device of the presentinvention could be implemented in several different ways and theapparatus disclosed above is only illustrative of the preferredembodiment of the invention and is in no way a limitation.

1. A method of making a drug delivery system, the method comprising: a)forming a recognitive polymeric hydrogel; and b) forming the recognitivepolymeric hydrogel into a contact lense with an anti-microbial.
 2. Themethod of claim 1, wherein forming a recognitive polymeric hydrogelcomprises forming a solution comprising amounts of a bio-template, afunctionalized monomer and a cross-linking monomer and initiatingcopolymerization of the functionalized monomer and cross-linkingmonomer.
 3. The method of claim 2, further comprising washing a portionof the bio-template from the recognitive polymeric hydrogel and loadingthe recognitive polymeric hydrogel with a drug.
 4. The method of claim3, wherein the anti-microbial is an anti-fungal agent.
 5. The method ofclaim 2, further comprising washing a portion of the bio-template fromthe contact lense and loading the contact lens with a drug by soakingthe contact lens in an aqueous drug solution.
 6. The method of claim 5,wherein the anti-microbial is introduced into the recognitive polymerichydrogel after the contact lens is formed.
 7. The method of claim 2,wherein the contact lens further includes a drug.
 8. The method of claim7, wherein the drug is selected from the group consisting of anantibiotic, an anti-inflammatory, an antihistamine, an antiviral agent,a cancer drug, an anesthetic, a cycloplegic, a mydriatics, a lubricantagent, a hydrophilic agent, a decongestant, a vasoconstrictor,vasodilater, an Immuno-suppressant, an immuno-modulating agent and ananti-glaucoma agent.
 9. The method of claim 4, wherein the anti-fungalagent is selected from the group consisting of Allyamines, non-azoleergosterol biosynthesis inhibitors, antimetabolities, Azoles, ChitinSynthase Inhibitors, Glucan Synthesis Inhibitors and Polyenes.
 10. Amethod of dispensing an anti-microbial in an eye biological tissue of ananimal comprising: a) forming a recognitive polymeric hydrogel matriximpregnated with the anti-microbial; and b) placing the recognitivepolymeric hydrogel in contact with a biological tissue to dispense thedrug.
 11. The method of claim 10, wherein the anti-microbial is ananti-fungal agent.
 12. The method of claim 10, wherein forming therecognitive polymeric hydrogel matrix comprises generating a solutioncomprising amounts of a bio-template, a functionalized monomer and across-linking monomer and initiating co-polymerization of thefunctionalized monomer and cross-linking monomer.
 13. The method ofclaim 12, wherein forming the recognitive polymeric hydrogel matrixproduces a contact lens.
 14. The method of claim 12, wherein thebio-template is the anti-microbial.
 15. The method of claim 14, whereinthe polymeric hydrogel matrix is further impregnated with a drug that isselected from the group consisting of an antibiotic, ananti-inflammatory, an antihistamine, an antiviral agent, a cancer drug,an anesthetic, a cycloplegic, a mydriatics, a vasodilater, a lubricantagent, a hydrophilic agent, a decongestant, a vasoconstrictor, animmuno-suppressant, an immuno-modulating agent and an anti-glaucomaagent.
 16. The method of claim 10, further comprising reloading therecognitive polymeric hydrogel matrix with the anti-microbial by soakingthe recognitive polymeric hydrogel matrix in an aqueous solution of thedrug.
 17. A system for delivering an anti-microbial drug through contactwith an eye of an animal, the system comprising a contact lens, thecontact lens comprising a hydrogel matrix with complexing sites thatcomplex the anti-microbial drug and release the anti-microbial agentfrom the hydrogel matrix over time while in contact with a surface ofthe eye.
 18. The drug delivery system of claim 17, wherein the hydrogelmatrix comprises silicon-base polymer chains.
 19. The drug deliverysystem of claim 17, wherein the complexing sites comprise amino acidfunctional groups.
 20. The drug delivery system of claim 17, wherein theanti-microbial is an anti-fungal agent.